Refrigeration system including a load control apparatus



'Jan. 13, 1948. E. LI S.CHULZ El AL 2,434,593

REFRIGERATION SYSTEM INCLUDING A LOAD CQNTROL APPARATUS Filed Feb. 2,- 1 946 INVENTOR. 4 JJL; Ml

y WA'M? Patented Jan. 13, 1948 REFRIGERATION SYSTEM INCLUDING A LOAD CONTROL APPARATUS Lakewood, Ohio, and Edward Edward L. Schulz,

A. Bailey, Marietta,

Corporation, Syracuse, N. 1.,

Delaware N. Y., assignors to, Carrier a corporation of Application February 2, 1946, Serial No. 645,185 3 Claims. (01. 62-2) This invention relates to the art of refrigera tion and more particularly to a control arrangement for regulating the production of refrigera tion effect, the control arrangement being responsive to variations in load-conditions to compensate for conditions of overload arising from unforeseen causes.

In air conditioning systems such as those used to condition buses, railway cars, etc., in which the compressor of the refrigeration system is driven directly from the engine of the bus, or a wheel of the car, it is desirable to provide somecontrol means to prevent inefficient and ineffective operation of the system under conditions-oi overload. In some systems heretofore used, a high pressure cut-out has been provided for such purpose, the cut-out serving to discontinue operation of the compressor until the undesirable con ditions have been remedied. It will be appreciated, however, in systems where'the compressor is driven directly, such cut-outs cannot be used.

The chief object of the present invention is to provide a simple and ready control means for preventing the passage of refrigerant to the evaporator of a refrigeration system whenever load conditions result in undesirably high condenser pressure.

An object of the present invention is to provide a simple control means for refrigeration systems used in transportation vehicles for air conditioning which operates automatically upon the failure of condenser cooling to prevent damage to the refrigeration system. V

A further object is to provide a refrigeration system embodying control means responsive to an increase in condenser pressure above a predetermined maximum which functions to prevent passage of refrigerant to the evaporator in cases where the system is unable to function effectively, and in which the system may be damaged or become inoperative by the failure of certain elements thereof.

A still further object is to provide a refrigeration system including a solenoid type valve in the discharge ,line disposed between the receiver and the expansion valve, the valveunder normal conditions remaining in open position and permitting free passage of refrigerant to the expansion valve and evaporator whilebeing actuated in response to excessive condensing pressure to move toward a closed position thus preventing the passage of refrigerant to the expansion valve.

A vstill further object is to provide a simple control for use in refrigeration systems in which is connected to discharge line 1 ing the flow of refrigerant erated and in which it is desired to prevent the passage of refrigerant to the evaporator under conditions of inefllcient or ineffective operation.

A still further object is to provide a refrigeration system for use in transportation vehicles for air conditioning in which thecom'pressor of the system is continuously operated and simple, efficient control means are provided to prevent the passage of refrigerant to the evaporator of the system under conditions in which the system is unable to function effectively.

This invention relates to a refrigeration system including in combination a compressor, a condenser, an expansion valve and an evaporator disposed in a closed circuit. A solenoid valve is disposed in the circuit between the condenser and the expansion valve and preferably between the receiver and the expansion valve. The solenoid valve is operable in response to a circuit breaker which is actuated by an increase in condenser pressure above a predetermined maximum. An increase in condenser pressure above a predetermined maximum actuates the solenoid valve to move it toward a closed position thus discontinuto the expansion valve and the evaporator.

The attached drawing illustrates diagrammatically a preferred embodiment Referring to the drawing, compressor 2 preferably of type although it may nected to a condenser 3 by a line 4. Refrigerant from condenser 3 flows through line 5 to receiver 6. 'Discharge line I connects receiver 6 with an of the invention.

there is shown a the reciprocating evaporator 8. An expansion valve 9 of the usual type well known in the art is disposed in discharge line I. Evaporator 8 is connected to compressor 2 by suction line ill. Condenser 3 may be air orvwater cooled as desired; as illustrated it may be air cooled by means of a suitable fan. Expansion valve 9 is actuated in the usual manner by means of a. bulb ll disposed adjacent the discharge end of evaporator 8. An equalizing line 12 extends between valve 9 and suction line Ill and serves to providexa pressure under the diaphragm of expansion valve 9 equal to the pressure at the discharge end of evaporator .8.

A control valve I3 is disposed in line 1 at a point preferably between receiver 6 and expansion valve 9. Control valve l3 may be a solenoid valve operable by means of coil H. A circuit breaker designated generally at I5 is provided. A diaphragm l6 forming a portion of member I5 through line l1 the compressor of thesgstemjsgontinuously opand is responsive to condenser pressure in line he of any desired type con- I 1. x switch n is provided adapted to be moved to open and closed positions. Leads i8 and II are provided, lead i8 extending from a source of supply to switch point 20, while lead it extends from the source of supply to coil 14. A second switch point It is connected to coil ll by line 22. An increase in condenser pressure above a predetermined level flexes diaphragm it, moving switch [8 out of contact with switch point 2| opening the circuit and permitting valve I3 to close to prevent passage of refrigerant to expansion valve 8.

When condenser pressure again decreases to the predetermined level diaphragm it closes the circuit by engaging switch i8 with switch point 2| opening valve [3 to permit free passage of refrigerant to expansion valve 9.

In the normal operation of the refrigeration system of my invention free passage of refrigerant is permitted to expansion valve 9 and evaporator 8 in accordance with the load imposed upon the system. Assuming pressure in discharge line I (condensing pressure) exceeds a predetermined maximum of say 200 pounds, such pressure is exerted through line H against diaphragm l8. Flexing of diaphragm l8 actuates circuit breaker l and serves automatically to close solenoid valve I3. If the fault in the system is due to impaired condensing action, such as a break-down of the condenser fan or a failure of water if the condenser be water cooled, the increase in condenser pressure above a predetermined maximum prevents the passage of refrigerant to the evapo- -rator and obviates damage to the system which might result. The control is automatic and consequently upon a decrease in condenser pressure the valve is actuated to open discharge line I permitting free passage of refrigerant to expansion valve 9.

In our co-pending applications, Serial Nos. 645,183, 645,184 and 645,186, filed February 2, 1946, February 2, 1946, and February 2, 1946, respectively, we have disclosed certain control means for modulating the action of the expansion valve in response to excessive loads imposed upon the system or in response to partial load conditions. It will be appreeiated'the present invention may be used in conjunction with the control arrangements disclosed in our co-pending applications if desired, or the present invention may be used alone in a refrigeration system to obviate harmful effects to the system which might result from operation under conditions of overload.

The present invention provides a simple and inexpensive means of control to prevent damage to arefrigeration system. The control means so provided is particularly desirable for use in refrigeration systems designed to be used in air conditioning applications such as transportation vehicles and the like. The control arrangement is responsive to condenser pressure above a predetermined level and operates automatically to prevent passage of refrigerant to the evaporator under conditions which might result in damage to the refrigeration system. The control arrangement is readily installed in existing systems and is of particular advantage when used in connection with refrigeration systems for buses.

While we have described and illustrated a preferred embodiment of our invention, it will be 4 understood our invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In a refrigeration system. the combination of a compressor. a condenser connected to the compressor, an expansion valve, a discharge line connecting the expansion valve and the condenser, an evaporator connected to the expansion valve, a suction line connecting the evaporator and the compressor, means disposed adjacent the suction line for governing operation of the expansion valve, a solenoid valve disposed in the discharge line adapted to prevent passage of refrigerant to the expansion valve, and means to operate the solenoid valve in response to an increase in condenser pressure above a predetermined level.

2. In a refrigeration system, the combination of a compressor, a condenser connected to the compressor. an expansion valve, a discharge line connecting the expansion valve and the condenser, an evaporator connected to the expansion valve, a suction line connecting the evaporator and the compressor, means disposed adjacent the suction line for governing operation of the expansion valve, a solenoid valve disposed in the discharge line, means for actuating the solenoid valve, said'means being responsive to an increase in condenser pressure above a predetermined level, an increase in condenser pressure above a predetermined level actuating said means to move the solenoid valve to a closed position preventing passage of refrigerant to the expansion valve.

3. In a refrigeration system, the combination of a compressor, a condenser connected to the compressor, an expansion valve, a discharge line connecting the expansion valve and the condenser, an evaporator connected to the expansionvalve, a suction line connecting the evaporator and the compressor, a solenoid valve disposed in the discharge line, and means for actuating the solenoid valve, said means including a circuit closing member, a diaphragm member to move said member to open and to close the circuit, and a line connecting the diaphragm member with the discharge line, the juncture of said line with the discharge line being disposed between the expansion valve and the condenser, an increase in pressure in the discharge line above a predetermined level actuating said diaphragm member to operate the circuit closing member thus tending to move the solenoid valve toward a closed position to prevent passage of refrigerant to the expansion valve.

EDWARD L. SCHULZ. EDWARD A. BAILEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

